Boards

I mean, c'mon. It's not that hard to work out. Wheels move, people sat on carts and stuff with wheels on them. Why didn't someone think "I could sit on these wheels and power it myself instead of a horse".?

Totally mental. Also consider that (apart form some unverified sketches) the bike first appeared around 1820-1830 as did the first cars. In fact the car was first conceptualised BEFORE then.

Literally, it's like a weird collective consciousness. If it hasn't been invented, most people just can't imagine it. But once it has, everyone can imagine it.

Like until the 14th century, NO ONE had ever used perspective in art. So tens of thousands of years of evidence of human drawing and no-one can even comprehend perspective, then suddenly, everyone does it and it becomes the norm.

If you want to get really deep about it, you could consider whether, say, humans even registered perspective as "a thing" before or if our visual understanding of the world became more sophisticated because of the impact of visionary artists?

Well it mainly has to do with the emergence of optical theory completely changing how people perceived the world.

A siimilar thing could be said for the way that photography revolutionised the way people painted objects in an out of focus. Everyone knew that the eye could focus on objects near and far, and not at the same time, but the idea that you would paint something that had sone objects in focus and others out of focus was only appreciated when photographs introduced the idea of a captured moment, rather than a whole scene over which your eye is able to wander and adjust.

i.e. well paved surfaces not being the norm, so a bike would be of limited utility in such circumstances, being restricted somewhat to the realm of curio or plaything and thus not receiving the necessary R&D attention.

You've flawed your own flaw with the second one
Roman roads were pretty limited, the vast majority of roads were just dirt tracks until recently. Again, impractical.
And wooden wheeled bikes would be heavy and shit and would break.

All the things that make bikes practical couldn't be made until the 19th century because our alien overlords hadn't bestowed us with their technology until then.

Which means there's less motivation for someone to solve the problem of getting from A to B quicker than walking by coming up with a really shit pseudo bike.

Also neatly ignores whether it was a problem that had been identified at all. If you've got walking for short distances and (I dunno) horses for medium to long distances, where's a problem that needs solving? Starting from the concepts of walking, wheels, and horses, why is a bike an obvious solution to that problem?

It only becomes obvious with hindsight.

Dunno why I'm explaining this here when I can be being paid megabucks for doing the same thing in my job.